CHAPTER 5STIMULUS AND RESPONSE
Stimulus and Response
Reference Signals
Stimulus and Response
duces a period of 16 nanoseconds because of rounding the result of the real division to an integer value.
Because the timescale in Sample 5-5 offers the necessary precision for a 7.5 nanoseconds half-period, only this model generates a 50percent duty-cycle clock signal with a precise 15 nanoseconds period.
Sample 5-3.Truncation errors in stim-ulus genera-tion
‘timescale 1ns/1ns
module testbench;
...
bit clk = 0;
parameter cycle = 15;
always
begin
#(cycle /2); // Integer division
clk =~clk;
end
endmodule Sample 5-4.Rounding errors in stim-ulus genera-tion
‘timescale 1ns/1ns
module testbench;
...
bit clk = 0;
parameter cycle = 15;
always
begin
#(cycle /2.0); // Real division
clk = ~clk;
end
endmodule Sample 5-5.Proper preci-sion in stimu-lus generation
‘timescale 1ns/100ps
module testbench;
...
bit clk = 0;
parameter cycle = 15;
always
begin
#(cycle/2.0);
clk = ~clk;
end
endmodule
Reference Signals
Stimulus and Response
Reference Signals Clock Multipliers
Implemented using PLLs.Many designs have a very high-speed front-end interface that is driven using a multiple of a recovered clock or the lower-frequency system clock. This clock multiplication is performed using an inter-nal or external PLL (phase locked loop). PLLs are inherently ana-log circuits. They are very costly to simulate in a digital simulator. When an internal PLL is used, the analog component that imple-ments the PLL is often modeled as an empty module. It is up to the testbench to create an appropriate multiplied clock signal in a behavioral fashion.
The reference clock could become the derived clock.A simple strategy is to reverse the role of the reference and derived clock. Since clock dividers are so easy to model, you could gener-ate the high-frequency clock then use it to derive the lower-fre-quency system-clock. Sample 5-9 shows a model for a multiply-by-4 clock generator using the divide-by-4 strategy. But this only works under two conditions: The reference clock is also an input to the design, and the frequency of the reference clock is known and fixed.
Synchronize the multiplied clock to the reference clock.The first condition can be eliminated by synchronizing the multi-plied clock signal with the reference clock. It will be possible to generate the multiplied clock signal even if the reference clock is supplied by the design. Sample 5-10 shows a model of a multiply-by-4 clock generator, synchronized with an input reference clock. But the problem of the hard-coded multiplied clock period remains. This model assumes a reference clock with an 80 nanoseconds period. What if the reference clock has a different frequency in a
Sample 5-8. Generating differential data signals wire [15:0] d;
bfm cpu(..., .d(d), ...);
design dut (..., .dp(d), .dn(~d), ...);
Sample 5-9. Generating clock multi-ples by divi-sion bit clk1 = 0;
bit clk4 = 0;
always
begin
repeat (4) #10 clk4 <= ~clk4; clk1 <= ~clk1;
end
Stimulus and Response
different simulation run? How can we generalize this model into a
generic clock-multiplier PLL model?
Measure the period of the ref-erence clock.Why not let the model learn the period of the reference signal? You can measure the time difference between two consecutive edges, divide this value by 4, and voila! A generic PLL model. Sample 5-11 shows a PLL model with a continuous measure of the reference signal. As the frequency of the reference clock signal changes, the frequency of the multiplied clock will adapt.
Sample 5-10. Synchroniz-ing multiplied clock to input reference clock always @(clk)
begin
clk4 <= ~clk4; clk4 <= #10ns clk4; clk4 <= #20ns ~clk4; clk4 <= #30ns clk4; end
Sample 5-11. Adaptive clock multi-plier model module pll(input bit ref_clk,
output bit out_clk);
parameter FACTOR = 4;
initial
begin
real stamp;
out_clk = 1’b0;
@(ref_clk);
stamp = $realtime;
forever begin
real period;
@(ref_clk);
period = ($realtime - stamp)/FACTOR; stamp = $realtime;
repeat (FACTOR-1) begin
out_clk = ~out_clk;
#(period);
end
out_clk = ~out_clk;
end
end
endmodule
Reference Signals
Stimulus and Response
of aligning objects. When writing a specification, you must be care-
ful that these implicit alignments do not create the illusion of a rela-
tionship. When reading a specification, do not assume a
relationship unless it is explicitly stated.
Generate unre-lated signals in separate threads.Sample 5-13 shows a better way to generate these unrelated clock signals. Since they are not synchronized in any way, they are gener-ated using separate concurrent threads. This separation will make it easier to modify the frequency of one signal without affecting the frequency of the other. Also, notice how each signal is explicitly skewed at the beginning of the simulation to avoid having the edges aligned at the same simulation time. This approach is a good prac-tice to highlight potential problems in the clock-domain crossing portion of the design. By varying these initial signal skew values, it will be possible to verify the correct functionality of the design across different asynchronous clock relationships.
Random Generation of Reference Signal Parameters
All signals are related in simu-lation.In the previous section, I explained why unrelated signals should be modeled as separate threads and skewed with respect to each other to avoid creating an implicit relationship that does not exist between them. The truth is: There is no way to accurately model unrelated signals. Each waveform is described with respect to the current simulation time. Because all waveforms are described using the same built-in reference, they are all implicitly related. Even though I made my best effort to avoid modeling any relationship between the two clock signals generated in Sample 5-13, they are related because of the deterministic nature of the simulator. Unless I manually modify one of the timing parameters, they will maintain the same relationship in all simulations.
Asynchronous means random.When we say that two signals are asynchronous to each other, we are saying that they have a random phase relationship. That phase relationship will be different every time and cannot be predicted. When I specified explicit skew delay values in Sample 5-13, I intro-
Sample 5-13. Generating unrelated waveforms bit clk100 = 0;
initial #2 forever #5 clk100 = ~clk100; bit clk33 = 0;
initial #5 forever #15 clk33 = ~clk33;
Reference Signals duced certainty where there wasn’t any. These delay values should be generated randomly to increase the chances that, over the thou-sands of simulation runs the design will be subjected to, any prob-lem related to clock skews will be highlighted.
Avoid using $random.One solution would be to call $random to generate the delay values, as shown in Sample 5-14. But this strategy can only produce evenly distributed delay values. It would not be possible to modify the dis-tribution of delay values toward more interesting corner cases, or constrain the delay values against each other to create interesting conditions.
Use skew vari-ables initialized with$random.Instead, as shown in Sample 5-15, use skew variables initialized using $random to determine the initial skew of each asynchronous waveform. Although it appears that little has been gained compared with Sample 5-14, this approach allows a testbench to modify or constrain the skew values. Notice the #1 delay inserted before the actual skew delay. This allows the testbench code, written in a pro-gram thread, to run and potentially replace the skew values before they are used. Sample 5-16 shows how a testbench can generate and replace new skew values with constrained random values that are deemed more interesting.
Sample 5-14. Generating unrelated waveforms using random skew bit clk100 = 0;
initial #({$random} % 10)
forever #5 clk100 = ~clk100; bit clk33 = 0;
initial #({$random} % 30)
forever #15 clk33 = ~clk33;
Sample 5-15. Generating unrelated waveforms using skew variables bit clk100 = 0;
int clk100_skew = {$random} % 10; initial #1 #(clk100_skew)
forever #5 clk100 = ~clk100; bit clk33 = 0;
int clk33_skew = {$random} % 30; initial #1 #(clk33_skew)
forever #15 clk33 = ~clk33;
Stimulus and Response
Reference Signals shown in Figure5-8 could appear to be violated. The race condition can be eliminated by using nonblocking assignments, as shown in Sample 5-18. Both clk and rst signals are assigned between timesteps when no blocks are executing. If the design under verifi-cation uses the falling edge of clk as the active edge, rst is already—and reliably—assigned.
Lack of main-tainability can introduce func-tional errors.The second problem, which is just as serious as the first one, is maintainability of the description. You could argue that the first problem is more serious, since it is functional. The entire simula-tion can produce the wrong result under certain conditions. Main-tainability has no such functional impact. Or has it? What if you made a change as simple as changing the phase or frequency of the clock. How would you know to change the generation of the reset signal to match the new clock waveform?
Conditions in real life are dif-ferent than those in this book.In the context of Sample 5-18, with Figure5-8 nearby, you would probably adjust the generation of the rst signal. But outside of this book, in the real world, these two blocks could be separated by hun-dreds of lines, or even be in different files. The specification is usu-ally a document three centimeters thick, printed on both sides. The timing diagram shown in Figure5-8 could be buried in an anony-mous appendix, while the pressing requirements of changing the clock frequency or phase was stated urgently in an email message. And you were busy debugging this other testbench when you received that pesky email message! Would you know to change the generation of the reset signal as well? I know I would not.
Model the syn-chronization within the gen-eration.Waiting for an apparently arbitrary delay cannot guarantee synchro-nization with respect to the delay of the clock generation. A much better way of modeling synchronized waveforms is to include the synchronization in the generation of the dependent signals, as shown in Sample 5-19. The proper way to synchronize the rst sig-
Sample 5-18. Race-free gen-eration of a synchronous reset bit clk = 0;
always #50 clk <= ~clk; bit rst = 0;
initial
begin
#150 rst <= 1’b1;
#200 rst <= 1’b0; end
Stimulus and Response
nal with the clk signal is for the generator to wait for the significant
synchronizing event, whenever it may occur. The timing or phase
of the clock generator can be modified now, without affecting the
proper generation of the rst waveform. From the perspective of a
design sensitive to the falling edge of clk,rst is reliably assigned
one delta-cycle after the clock edge.
Reset may need to be applied repeatedly dur-ing a simulation.There is a problem with the way the rst waveform is generated in Sample 5-19. The initial block runs only once and is eliminated from the simulation once completed. There is no way to have it exe-cute again during a simulation. What if it were necessary to reset the device under verification multiple times during the same simu-lation? An example is the “hardware reset” testcase that verifies proper reset operation: After setting some internal registers, the hardware reset must be applied to verify that these registers return to their reset value. The ability to control reset application is also very useful. This control lets testbenches perform preparatory oper-ations before resetting the design and starting the actual stimulus.
Generate reset from within a module task.The proper mechanism to encapsulate statements that you may need to repeat during a simulation is to use a task as shown in Sam-ple 5-20. To repeat the reset signaling, simply call the task. To maintain the behavior of using an initial block to reset the device under verification automatically at the beginning of the simulation (which may or may not be desirable), simply call the task in an ini-tial block.
Reset task should be in pro-gram.It will be possible to invoke the reset task in the module from the testbench program threads. The testbench will thus be able to reset the design any time the reset is required. An alternative would be to put the reset task in a program task, as shown in Sample 5-21.
Sample 5-19. Proper genera-tion of a syn-chronous reset bit clk = 0;
always #50 clk = ~clk; bit rst = 0;
initial
begin
@ (negedge clk);
rst <= 1’b1;
@ (negedge clk);
@ (negedge clk);
rst <= 1’b0;
end
Reference Signals
Because modules cannot call program tasks, it will be necessary for each testbench to call the reset program task to reset the DUT.However, this gives the testbench better control over the reset parameters and its coordination with other device stimuli, not just the clock. The section titled “Simulation Control” starting on page 124 of the Verification Methodology Manual for SystemVerilog defines a simulation sequence methodology that includes a pre-defined step for applying hardware reset to the design under verifi-cation.
Sample 5-20.Encapsulating the generation of a synchro-nous reset
module tb_top;
bit clk = 0;
bit rst = 0;
always #50 clk = ~clk;
...
task hw_reset
rst = 1’b0;
@ (negedge clk);
rst <= 1’b1;
@ (negedge clk);
@ (negedge clk);
rst <= 1’b0;
endtask: hw_reset
initial hw_reset ;
...
endmodule Sample 5-21.Synchronous reset program task.
program test;
task hw_reset
tb_top.rst <= 1’b0;
@ (negedge tb_top.clk);
tb_top.rst <= 1’b1;
@ (negedge tb_top.clk);
@ (negedge tb_top.clk);
tb_top.rst <= 1’b0;
endtask: hw_reset
initial
begin
hw_reset;
...
end
endprogram
Stimulus and Response
Simple Stimulus
Stimulus and Response
Simple Stimulus Instead of providing test vectors to perform these operations repeat-edly, why not provide subprograms that perform these operations? All that will be left is to call the subprograms in the appropriate order with the appropriate data.
Try to apply the worst possible combination of inputs.The task to perform the synchronous reset is very simple. It needs to assert the rst input, then wait for the active edge of the clock. But what about the other inputs? You could decide to leave them unchanged, but is that the worst possible case? What if the reset was not functional and the device loaded one of the inputs and that input was set to 0? It would be impossible to differentiate the wrong behavior from the correct one. To create the worst possible condi-tion, both d0 and d1 inputs must be set to 1. The sel input can be set randomly, since either input selection should be functionally identi-cal. An implementation of the reset procedure is shown in Sample 5-26.
Sample 5-25. Test vectors for 2-to-1 input sync reset D flip-flop clocking cb @ (negedge tb_top.clk); output #1 data = {tb_top.rst,
tb_top.d0,
tb_top.d1,
tb_top.sel}; endclocking: cb
initial
begin
// Input
@(cb); cb.data <= 4’b1110;
@(cb); cb.data <= 4’b0100;
@(cb); cb.data <= 4’b1111;
@(cb); cb.data <= 4’b0011;
@(cb); cb.data <= 4’b0010;
@(cb); cb.data <= 4’b0011;
@(cb); cb.data <= 4’b1111;
...
end
Sample 5-26. Abstracting the synchro-nous reset operation task sync_reset;
begin
cb.rst <= 1’b1;
cb.d0 <= 1’b1;
cb.d1 <= 1’b1;
cb.sel <= $random; @(cb);
endtask: sync_reset
Stimulus and Response
新闻评论的格式写法 新闻评论的格式写法新闻评论的文体结构与其他新闻文体相比基本是一致的，它包括标题、导语、主体、结尾四个部分，而在具体写作新闻评论时，各个构成部分又有其独特的写法。1．引人注意的标题新闻评论的标题既可以标明论题的对象和范围，也可以直接提出评论的观点和主旨；总的要求是生动活泼、言简意赅，使标题成为引人耳目的招牌。首先，要巧用动词，强化动词在评论标题中的动态感和鲜活感。2005年11月4日《经济日报》的评论《扬起企业品牌之帆》，这篇评论的标题用动词“扬起”，既揭示出我国目前实施自主品牌的必要性，也展现了我国企业界创新品牌的信
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注意：每道题的难度等级不同，*越多，难度等级越高。可以根据自己的能力，选做恰当难度的题。 8.1改写第五章编程练习5.4题的程序，使该程序在程序结束之前，先判断字典内容是否发 生了变化（单词的添加、修改、删除）。如果字典内容已经被修改，则提示是否保存修改后的新字典；若选择保存，则将字典的全部内容写入一个纯文本文件，该文件可以命名为dictionary.txt。每次程序重新运行时，先尝试打开dictionary.txt。如果该文件存在，则打开文件，并从该文本文件中输入产生一个字典。 难度等级：** 8.2编写一个用于统计英文纯文本文件的各项信息：文件内容的总字符数（包括标点符号）， 单词个数，文本行数。 要求： 1.提示用户输入一个扩展名为.txt的纯文本文件名，如果指定文件存在，则打开该文 件，否则显示错误提示信息。 2.统计文件内容的上述信息，并显示所统计的信息。信息的显示格式自行确定，例如 可以按如下格式显示： 文件名：Information.txt 字符数：4854 单词数：853 文本行数：56 3.每个文件的信息显示后，提示用户是否继续统计其他文本文件，如果继续，则重复 1和2中的操作。 提示： 1.判断文本行的依据可以是每行的结尾应为‘\n’。 难度等级：*
8.3编写一个程序用于某大学的某信息专业学生的基础课成绩的录入、显示和相应数据文件 的读写。 要求： 1.成绩的按如下顺序录入： ⑴在学生成绩录入之前，先通过输入确定基础课程的门数和课程名称。例如： 基础课程1：高等数学 基础课程2：大学物理 基础课程3：大学英语 基础课程4：C语言程序设计 基础课程5：数据结构 … ⑵每个学生的成绩录入的内容包括学生的姓名、学号、性别和各门课程的成绩。成 绩按照A,B,C,D四个等级划分。录入格式可以参照如下： 姓名：李建国 学号：200410001 性别：男 高等数学：C 大学物理：B 大学英语：C C语言程序设计：B 数据结构：A … 2.保存学生成绩数据的文件的种类和结构、内容如下 ⑴课程信息索引文件courses.inx用于保存所有课程的索引信息，每门课程的索 引信息由课程索引序号和课程名组成。例如： 课程序号课程名 1高等数学 2大学物理 3大学英语 4C语言程序设计 5数据结构 … 注意，课程门数不得少于5门。 ⑵学生信息文件student.inx用于保存所有学生的索引信息，每个学生的索引信息 由学号和学生基本信息（姓名、性别）组成。例如： 学生学号学生基本信息 200410001李建国，男 … ⑶分课程成绩数据索引文件XXX.inx用于保存一门课程的所有学生成绩的索引信 息，每个学生的成绩索引信息由学号和成绩等级组成。每门课程有一个成绩数据 索引文件，文件名XXX由课程名确定。例如： 文件名：“高等数学.inx” 学生学号成绩等级 200410001C
CoverLetter英文简历书写模板 Writing the Cover Letter Writing the Cover Letter What is A Cover Letter? What is A Cover Letter Writing: Invitation to find out Persuasive Writing: Invitation to find out more about you and land Targeted Response to A Job Description and/or a Particular organization and/or a Particular organization—— THESE QUESTIONS: Can you do the job? Can you do the job? Will you do the job? Will you do the job? Will you fit in? Will you fit Cover Letter Four Steps for Cover Letter Writing From https://www.doczj.com/doc/f34140618.html, Writing From https://www.doczj.com/doc/f34140618.html, 1. 1. Conduct Research on The Conduct Research on The Organization Organization 2. 2. Deconstruct the job or internship Deconstruct the job or internship description description 3. 3. Consolidate and prioritize the key Consolidate and prioritize the key requirements you have extracted requirements you have extracted 4. 4. Plug yourself into the organizational Plug yourself into the organizational and job requirements and job requirements The Job Description The Job Description Climate and Energy Program (CEP) Climate and Energy Program (CEP) Internship, WRI Internship, WRI Position Summary WRI's Climate and Energy Program (CEP) seeks a WRI's Climate and Energy Program (CEP) seeks a motivated, well motivated, well--organized, and detail organized, and detail--oriented oriented intern to support our climate change and energy intern to support our climate change and energy policy work. The successful candidate will support policy work. The successful candidate will support CEP staff in a wide variety of activities including CEP staff in a wide variety of activities including publications management, event coordination, publications management, event coordination, database management, financial management, database management, financial management, and other tasks related to general program and other tasks related to general program administration. administration. 1. Research: 1. Transport Climate, Energy and Transport Division Projects: Division Projects: ––COP COP--15: Countdown to Copenhagen 15: Countdown to Copenhagen ––U.S. Federal Climate Policy U.S. Federal Climate Policy ––International & U.S. Action International & U.S. Action ––Business & Markets Business & Markets ––Technology & Green Power Technology & Green Power ––Energy Security & Climate Change Energy Security & Climate Change ––Information & Analysis Tools Information & Analysis Tools 1. Research: 1. Research: World Resources Institute --18, 2009, the world will 18, 2009, the world will convene in Copenhagen, Denmark to create convene in Copenhagen, Denmark to create a new global climate agreement to reduce a new global climate agreement to reduce greenhouse gas emissions at the greenhouse gas emissions at the United United Nations Climate Change Conference Nations Climate Change Conference (COP (COP-- experts have been actively involved in WRI’s experts have been actively involved in the negotiations leading up to the negotiations leading up to COP COP--15 15 and and are analyzing various dimensions of a new are analyzing various dimensions of a new agreement, among them: Vulnerability and agreement, among them: Vulnerability and Adaptation; Adaptation; Forestry and Reduced Emissions Forestry and Reduced Emissions for Degradation and Deforestation (REDD); for Degradation and Deforestation (REDD); Technology and Technology Transfer; Technology
小学生新闻消息写法技巧 导读：消息的特点 1、短小精练：消息要短小精练，这是新闻写作的基本要求。就小记者采写新闻来说，写好短消息，便于迅速及时的报道新闻事实，同时也锻炼小记者的采写能力;就读者阅读新闻来说，它便于阅读。 2、语言生动简洁：消息的语言只有生动、简洁，才能吸引读者 3、“倒金字塔”结构：消息的写作是将最重要、最新鲜的事实写在新闻的最前面，按事实重要性程度和读者关注的程度先主后次的安排，内容越是重要的，读者越是感兴趣的'，越要往前安排，然后依次递减。这在新闻写作中称为“倒金字塔”结构。 二、消息导语的几种写作方法 1、叙述式导语的写作：就是直截了当地用客观事实说话，通过摘要或概括的方法，简明扼要地反映出新闻中最重要、最新鲜的事实，给人一个总的印象，以促其阅读全文。 2、描写式导语的写作：记者根据目击的情况，对新闻中所报道的主要事实，或者事实的某个有意义的侧面，作简练而有特色的描写，向读者提供一个形象，给人以生动具体的印象，这就是描写式导语的一般特点。一般用在开头部分，以吸引读者，增强新闻的感染力。 3、议论式导语的写作：往往采用夹叙夹议的方式，通过极有节制、极有分寸的评论，引出新闻事实。一般分为三种形式：评论式、引语式、设问句。
三、学会恰当运用新闻背景材料 背景材料在不少新闻中占据一定的位置，是新闻稿件中不可缺少的内容。交代背景应根据需要因稿而异，更要紧扣主题，还有交代背景时不宜太多，材料要写的生动活泼。 【小学生新闻消息写法技巧】 1.小学生新闻消息的写法技巧 2.新闻消息的写作方法 3.新闻通讯的写法 4.盘点新闻消息写作方法大全 5.2015年新闻时事评论的写法 6.有关将新闻稿改写为消息 7.2015新闻的写作基础知识：消息的写作 8.新闻宣传报道的格式与写法 上文是关于小学生新闻消息写法技巧，感谢您的阅读，希望对您有帮助，谢谢
分享两篇SCI发表的经历 三年前对于我来说SCI就是天书一样，在我踏进博士的门槛后我以为自己进入了地狱，也纠结也彷徨，整天刷虫友们对于博士、SCI的帖子，我选择了虫友们鼓励的那一部分来激励自己继续前行。我告诉自己坚持就是胜利，当然那是积极的坚持。在好几月之前就有这个想法，今天早上收到第二篇的接收通知后，我便想今天一定要在小木虫上谢谢那些给予我帮助的虫友们。 话不多说，我把自己这两篇投稿的经历与大家共享，希望能给大家带来一点点用处。 第一篇发表在Fitoterapia Cover letter Dear Editor Verotta: We would like to submit the manuscript entitled "××××××题目" by ××××××所有作者姓名which we wish to be considered for publication in Journal of Fitoterapia. All authors have read and approved this version of the article, and due care has been taken to ensure the integrity of the work. Neither the entire paper nor any part of its content has been published or has been accepted elsewhere. It is not being submitted to any other journal. We believe the paper may be of particular interest to the readers of your journal as it is the first time of ××××××研究的精华所在 Thank you very much for your reconsidering our revised manuscript for potential publication in Fitoterapia. We are looking forward to hearing from you soon. Correspondence should be addressed to Jinhui Yu at the following address, phone and fax number, and email address. 地址、学院、学校名称 Phone: + 86×××××× Fax number: + 86571××××××
1、新闻要素：不可忽略5W1H。（Who、What、When、Where、Why、How） 2、新闻构成：题、文、图、表。 3、题：简要、突出、吸引人。 4、文：导语100至200字：开宗明义，人事时地物。 5、主体300至500字：深入浅出，阐扬主旨。 6、结语100字：简洁有力，强调该新闻的意 义与影响，或预告下阶段活动。7、图：视需要加入有助于读者理解的图片。 8、表：视需要加入有助于读者理解的表格。9、写作要律：具有新闻价值、正确的格式、动人的标题。简洁切要的内容、平易友善的叙述、高度可读性、篇 幅以1至2页为宜（一页尤佳）。写作技巧：清晰简洁、段落分明、使用短句、排版清爽。切忌偏离事实、交代不清、内容空洞。一篇好的新闻稿除了必须具有 新闻价值、把握主诉求与正确的格式外，行文应力求简洁切要，叙述应有事实基础，文稿标题则以简要、突出、吸引人为原则，用字要避免冷僻艰深，以提高文 稿的可读性。此外，篇幅也不宜长篇大论，一般以1至2页为原则，必要时可以加入图表，增加文稿的专业性，切忌内容空洞、语意不清、夸大不实。 倒金字塔结构是绝大多数客观报道的写作规则，被广泛运用到严肃刊物的写作 中，同时也是最为常见和最为短小的新闻写作叙事结构。内容上表现在在一篇新闻中，先是把最重要、最新鲜、最吸引人的事实放在导语中，导语中又往往是将 最精彩的内容放在最前端；而在新闻主体部分，各段内容也是依照重要性递减的 顺序来安排。犹如倒置的金字塔，上面大而重，下面小而轻。此种写作方式是目 前媒体常用的写作方式，亦即将新闻中最重要的消息写在第一段，或是以「新闻提要」的方式呈现在新闻的最前端，此种方式有助于媒体编辑下标题，亦有助于阅听人快速清楚新闻重点。基本格式（除了标题）是：先在导语中写一个 新闻事件中最有新闻价值的部分（新闻价值通俗来讲就是新闻中那些最突出，最
Dear Editors and Reviewers, Thank you for your letter and comments on our manuscript titled “Temporal variability in soil moisture after thinning in semi-arid Picea crassifolia plantations in northwestern China” (FORECO_2017_459). These comments helped us improve our manuscript, and provided important guidance for future research. We have addressed the editor’s and the reviewers’comments to the best of our abilities, and revised text to meet the Forest Ecology and Management style requirements. We hope this meets your requirements for a publication. We marked the revised portions in red and highlighted them yellow in the manuscript. The main comments and our specific responses are detailed below: Editor: Please explain how the results in this paper are significantly different from those in Zhu, X., He, Z.B., Du, J., Yang, J.J., Chen, L.F., 2015. Effects of thinning on the soil moisture of the Picea crassifolia plantation in Qilian Mountains. Forest Research. 28, 55–60.)
Case 1 Dear Editor, We would like to submit the enclosed manuscript entitled "GDNF Acutely Modulates Neuronal Excitability and A-type Potassium Channels in Midbrain Dopaminergic Neurons", which we wish to be considered for publication in Nature Neuroscience. GDNF has long been thought to be a potent neurotrophic factor for the survival of midbrain dopaminergic neurons, which are degenerated in Parkinson’s disease. In this paper, we report an unexpected, acute effect of GDNF on A-type potassium channels, leading to a potentiation of neuronal excitability, in the dopaminergic neurons in culture as well as in adult brain slices. Further, we show that GDNF regulates the K+ channels through a mechanism that involves activation of MAP kinase. Thus, this study has revealed, for the first time, an acute modulation of ion channels by GDNF. Our findings challenge the classic view of GDNF as a long-term survival factor for midbrain dopaminergic neurons, and suggest that the normal function of GDNF is to regulate neuronal excitability, and consequently dopamine release. These results may also have implications in the treatment of Parkinson’s disease. Due to a direct competition and conflict of interest, we request that Drs. XXX of Harvard Univ., and YY of Yale Univ. not be considered as reviewers. With thanks for your consideration, I am Sincerely yours, case2 Dear Editor, We would like to submit the enclosed manuscript entitled "Ca2+-binding protein frequenin mediates GDNF-induced potentiation of Ca2+ channels and transmitter release", which we wish to be considered for publication in Neuron. We believe that two aspects of this manuscript will make it interesting to general readers of Neuron. First, we report that GDNF has a long-term regulatory effect on neurotransmitter release at the neuromuscular synapses. This provides the first physiological evidence for a role of this new family of neurotrophic factors in functional synaptic transmission. Second, we show that the GDNF effect is mediated by enhancing the expression of the Ca2+-binding protein frequenin. Further, GDNF and frequenin facilitate synaptic transmission by enhancing Ca2+ channel activity, leading to an enhancement of Ca2+ influx. Thus, this study has identified, for the first time, a molecular target that mediates the long-term, synaptic action of a neurotrophic factor. Our findings may also have general implications in the cell biology of neurotransmitter release. 某杂志给出的标准Sample Cover Letter Case 3 Sample Cover Letter Dear Editor of the : Enclosed is a paper, entitled "Mobile Agents for Network Management." Please accept it as a candidate for publication in the . Below are our responses to your submission requirements. 1. Title and the central theme of the article. Paper title: "Mobile Agents for Network Management." This study reviews the concepts of mobile agents and distributed network management system. It proposes a mobile agent-based implementation framework and creates a prototype system to demonstrate the superior performance of a mobile agent-based network over the conventional client-server architecture in a large network environment.
新闻写法——消息写作 各位同仁，大家下午好！今天我很荣幸坐在这里同大家一起学习探讨有关新闻的写作技巧，但愿我讲的内容对各位有点启发。分两部分：一是消息，二是通讯。 天下文章，总体来说，都是一个写什么、怎么写的问题。写什么不仅是内容，还有一个形式问题；怎么写是技术问题。新闻是文章种类中一种特殊的文体，怎么写又有它特别的规范。是不是不自由了呢？不是，规范只是一个大笼子，在笼子里可以自由飞翔。 新闻是思想的产物，是意识形态。不是纯客观，不可有闻必录。同时，新闻不是公文，不是法律，不是判决书。读者自由地接受新闻事实，自由地作出判断。新闻以事实形成舆论，左右社会，“人言可畏”，“千夫所指，不疾而亡。”新闻写作提高表达技巧十分重要。 在这里，我先介绍一下消息的写作，这是目前适用最广泛的一种新闻写作方式。对于我们这些从事新闻报道的基层通讯员来说，也是最常用的文体，最容易发稿见报的文体。困为通讯较消息篇幅长、覆盖面大，像我们基层的乡镇、县直单位，一般很难被上级新闻单位采用。 一、什么是消息。 1、消息的定义。消息，就是用最简要和迅速的手段报道最近发生事件的一种新闻宣传文体。也就是说新闻消息就是告诉人们发生了什么，报道最近发生的事实。狭义的新闻就是指消息，它是新闻体裁的重要形式，是报纸和广播电视新闻的主角，其它新闻报道如通讯、广播稿、新闻评论等是它的发展和补充。学会消息写作便意识着掌握了打新闻写作大门的钥匙。我们初学新闻的同志在看报读报时，看到的“本报讯、本刊讯、新华社南昌讯、据**社**讯”等开头的，都称之为消息，我们常说的“豆腐块”，任何一张报纸都有若干条消息。 2、消息的特点：（一）采写发稿迅速、及时，叙事直截了当，语言简洁明快，篇幅短小；（二）消息5W+1H，whe何时、where何地、who何人、what何事、why何故、how如何；（三）在结构上，消息一般由标题、导语、主体、背景和结尾五个部分组成，有“倒金字塔结构”与“非倒金字塔结构”两大类。 3、消息的种类：(一)动态消息：也称动态新闻，这种消息迅速、及时地报道国内国际的重大事件，报道社会主义建设中的新人新事、新气象、新成就、新经验。动态消息中有不少是简讯(短讯、简明新闻)，内容更加单一，文字更加精简，常常一事一讯，几行文字。(二)综合消息：也称综合新闻，指的是综合反映带有全局性情况、动向、成就和问题的消息报道。 (三)典型消息：也称典型新闻，这是对某一部门或某一单位的典型经验或成功做法的集中报道，用以带动全局，指导一般。(四)述评消息：也称新闻述评，它除具有动态消息的一般特征外，还往往在叙述新闻事实的同时，由作者直接发出一些必要的议论，简明地表示作者的观点。记者述评、时事述评就是其中的两种。 以上四类消息，以动态消息较易写作，大家可以经常练习写一些，从实践中提高新闻写作能力。
实验输入输出流 一、实验目的 1、掌握文件字节流的用法； 2、掌握文件字符流的用法； 3、掌握缓冲流的用法； 二、实验内容与步骤 1、编写程序，实现将诗句写入c:\小池.txt文件中，然后再从该文件中读出并打印输出。宋诗《小池》 作者：杨万里 泉眼无声惜细流， 树荫照水弄轻柔。 小荷才露尖尖角， 早有蜻蜓立上头。 import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.util.Scanner; public class PoemWrite { public static void main(String[] args) { Scanner reader=new Scanner(System.in); String s; try{ FileWriter outOne=new FileWriter("c:\\小池.txt"); BufferedWriter outTwo=new BufferedWriter(outOne); while(!(s=reader.nextLine()).equals("0")){ outTwo.write(s); outTwo.newLine(); } outTwo.flush(); outTwo.close(); outOne.close(); FileReader inOne=new FileReader("c:\\小池.txt"); BufferedReader inTwo=new BufferedReader(inOne); while((s=inTwo.readLine())!=null){
消息导语的写法 导语是消息的重要组成部分，是消息的开头，通常是指消息的第一个自然段。消息导语的写作，是新闻记者的基本功。美国大学新闻学院的大学生或研究生要花一年的时间专门学习导语的写作。许多人构思和写作导语的时间要占据通篇稿件的三分之一到一半。由此可见导语写作的难度和重要性。 导语最基本的要求是言简意赅，即用最简洁凝炼的语言将消息中最新鲜、最主要、最精彩、最生动、最吸引人的新闻事实表现出来。导语的写法千变万化、灵活多样。概括起来，大致可以分为下列8种。 一、概要式：即用叙述的方式来归纳概括新闻的要点。 如：新华社1949年4月22日电人民解放军百万大军，从一千余华里的战线上，冲破敌阵，横渡长江。 再如：本报讯中国科学院昆明动物研究所培育计划中的第一只白猴于5月1日降生。（1988年全国好新闻消息二等奖，原载《云南日报》1988 年6月29日一版） 再如：本报讯（记者李捷）613万考生迎来了他们一生一博的时刻-2003年非典时期的正常高考今天静静拉开帷幕。（第十四届中国新闻奖二等奖消息作品） 一、描写式：即用现场目击、白描勾勒的方式来切入。 如：新华社北京1982年7月16日电（记者郭玲春）鲜花、翠柏丛中，安放着中国共产党员金山同志的遗像。千余名群众今天默默走进首都剧场，悼念这位人民的艺术家o（第四届中国新闻奖消息一等奖作品） 再如：本报讯（记者健吾）古埃及的金字塔、法国的巴黎圣母院、缅甸的仰光大金塔、加拿大的尼亚加拉瀑布，还有列宁的墓、白求恩的故居以及日本的劈啪舞……人们不用出国，在五泉山公园文昌宫举行的《劳崇聘外国风光写生展览》上，便可欣赏到外国的名胜古迹，领略到外国的风土人情。（原载《兰州晚报》1985年10月8日四版）再如：本报讯（记者健吾）大西北一个偏僻山村的崎岖小道上，一支娶亲的人马抬着花轿，拥着新郎入场，由此引出一个凄凉的、为人们所熟悉 却又弄不清发生在何年何月的故事。这是省歌剧团为建国40周年正在排练的献礼之作——《阴山下》的序幕o（《兰州晚报》1989年3月5日四版） 三、提问式：即先提出问题，引出悬念，进而解答。
实验十一流类库与输入／输出(2学时) 一、实验目的 1．熟悉流类库中常用的类及其成员函数的用法。 2．学习标准输入输出及格式控制。 3．学习对文件的应用方法(二进制文件、文本文件)。 二、实验任务 1．观察以下程序的输出，注意对输出格式的控制方法； //labll—1．cpp #include 四．我的论文生活 本人现在5篇SCI，两篇IEEE TRANSACTION/JOURNAL (regular) paper，两篇IF=1.2*，一篇IF=0.8*.一个专利，两个应用证明。还有5篇SCI在审，IF分别为2.3*，0.5*，0.5*，0.4*，0.4*。所以我自认为在博士期间做的还可以，再加上博士期间做了太多的秘书工作，同时接手的项目自己独立完成，还是我以前没有接触的领域，也是实验室没有接触过的领域，所以我自己对自己还是比较满意的。当然在理工同窗面前我是非常普通，甚至不入流的学生之一，不过我希望把我一点经验分享大家，如果对于学弟学妹有一点帮助，我就非常开心了，如果没有帮助也请各位大牛不要见笑。下面我介绍一下我写论文的经验。 打铁还需自身强啊。首先我们应该从我们自己本身着手。博士与本科和硕士相比都不同，而且是根本上意义的不同。打个比方，如果给大家一个问题，大家能够非常快速的解决，并利用各种方法。但是这种训练方式完全是自下而上的教育方式，一直到硕士戛然而止。博士突然让我们思维方式出现了一个转变，这是很难的。这种原因可能因为我们小学到硕士一直是按照我们自己的思维方式在培养，到了博士我们学习西方思维方式培养，而产生了极大的落差。 博士不会在告诉你，你需要解决什么样的具体问题，而是在于你是否能发现问题。我们一直的教育都是我们解决问题的能力，对于中国的学生，特别是在理工大学培养的学生，解决问题的能力绝对是非常强的，没有任何问题，但是缺少一双发现问题的眼睛。我们不善于自己提出问题和解决我们觉得陌生的问题，我们喜欢解决别人提出来的问题，使用别人提出的方法，按照别人的思路。不能说孰优孰劣，但是在现有的博士培养体系下我们是处于劣势的。郑强教授说得对，如果找不到与自己发现问题相关的参考文献，通常我们都对自己的发现先产生怀疑，极度的不自信。 我们需要在别人研究内容的基础上发现存在的问题。例如某个同学会说，某某领域已经做烂了，没有东西做了。但是我要告诉你，把你放着一个新的领域，你还是不行。因为不是没有问题，而是你没有发现问题。这个劣势在工科中尤为突出。这样我们在读某篇论文或者某位牛人的大作的时候，读完了直呼精彩，但是我们这个时候就需要考虑这篇论文的问题在哪里，有没有限制条件，我们能不能发现新的问题，在我们解决新的问题的时候也是我们有目的的资料收集的时候，也就是我们写论文的时候，发论文的时候了。不过需要强调的是，思路对也好，不对也好，方法对也好，不对也好，除了结果不同以外，其他都是一样的。过程都是痛苦的，甚至会因为发现自己是如此的无知而感到深深的惭愧和不能接受。 上面的论点对于大多数人来说，大而空，该不懂还是不懂，该写不出来还是写不出来，没有办法，这个就是思维的问题。那么上面从自身入手，我再给出从外界获取资源的方法。只有将二者结合才能达到最佳结果。 如何获取外界资源。我看论文的时候，会有很多问题，论文中很多观点我看不懂，而且这些观点在论文中没有任何的解释，让我摸不着头脑，所以我会给论文的通信作者写信咨询。我的经验是别给中国人写信。中国人不喜欢Share，只喜欢require。下面我附上一封我写信请教问题的模板。 Dear and respected Prof. *** I am very sorry for troubling you, but can I ask you a question relevant to your paper? 1、实体、对象与类的概念 2、类的定义 3、对象声明与引用 4、私有、公有与保护 5、日期类的设计 6、两种程序设计思想 7、汽车类的设计 8、几何图形圆类的设计 9、构造函数的定义10、重载构造函数11、析构函数的定义12、整数翻译函数13、实际意义的析构函数14、Person类的设计15、对象与指针16、this指针 ?实体：指客观世界存在的某个事物?一所大学，例如：西安交通大学 ?某动物，例如：一只羊 ?一本图书，例如：《C++程序设计教程》?一篇文章，例如：“羊年趣赏羊联” ?一个专业班级，例如：材料21班 ?一名学生，例如：材料21班的蒋贵川?…… ?可以拍摄视频描述实体 ?也可以写一篇文章描述实体 ?我们设计的程序都是为了求解某个(些)问题 ?如果求解的问题中涉及到某个实体，那么在程序中如何描述实体呢？ ?通过对实体进行抽象，来描述实体 ?每个实体都有其特征和功能，特征和功能通称为属性?实体与实体的不同在于属性的不同 ?所谓抽象描述实体是指： ?从实体中抽取出若干特征和功能，来表示实体 ?特征指实体的静态属性，功能指实体的动态属性 ?对实体加以抽象要注意下面两点： ?移出细节看主干 ?不是借助具体形象反映现实，而是以抽象表达科学的真实 毕加索画《牛》 1945年12月5日 1946年1月17日 ?形体逐渐概括 ?线条逐步简练 ?别人认为的终点，他 作为起点 ?每幅画不重复 ?精炼地表现了公牛的 ?电视机的特征：?型号?尺寸?液晶?价格? ……?电视机的功能： ?播放影视?选频道?调颜色?调音量?……投稿经验
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